基于湍动能输运的一方程转捩模型

One-Equation Transition Model Based on Turbulent Kinetic Energy Transport

传统转捩模型的构造十分依赖转捩机理的发现和理解,对机理的模化也存在误差。本文基于尺度自适应的KDO湍流模型,以输运变量r=μt/μ重新标定模型参数,使模型整体达到了流动结构自适应,可实现湍流/转捩一体化计算。根据长度尺度的不同,可细分为KDO-tran和CKDO-tran模型。CFD计算评估了经典的T3A,T3B平板边界层旁路转捩,T3A-平板边界层自然转捩,Aero-A翼型分离泡转捩,DLR-F5,6:1椭球横流转捩及可压缩平板边界层、尖锥转捩。该模型无法精确捕捉层流-湍流的过渡,但能准确捕捉转捩的起始位置(Transition onset),在高Re数、复杂流动的表现尤其突出。该模型捕捉转捩的机制在于流动结构的自适应和湍流输运特性的保存,不引入任何转捩机理却能捕捉多种类型的转捩现象,具有较好的适用性。

The traditional transition model heavily depends on the discovery and understanding of the transition mechanisms,and there are errors in the modeling process.The KDO Scale-Adaptive-Simulation model is selected as the base model,the coefficient of which is recalibrated with the transport variable r=μt/μ.Depending on the scales,it can be subdivided into KDO-tran and CKDO-tran models.CFD simulations of classic T3 A,T3 B flat plate bypass transitions,T3 A-flat plate natural transition,Aero-A airfoil separation bubble transition,DLR-F5,6:1 spheroid cross-flow transition,compressible boundary layer transition and supersonic cone transition are performed.The turbulence/transition integrated model can not precisely capture the region between laminar and turbulent flows but accurately captures the transiton onsets and the peak friction values after transition.Especially at high Re numbers,the performance in complex flow is particularly prominent.The model does not introduce any transition mechanism but can capture many types of transition phenomenon,with high reliability.The key is the preservation of transport and flow-structure adaptive features of the fluid.